Telecommunications companies have been warned to improve customer service after a jump in complaints about internet services and a high number of mobile phone woes.

Some 17,777 complaints were made to the Telecommunications Industry Ombudsman from January to March 2023, similar to the previous reporting period.

Almost half were about mobile phones while about a third related to internet services, representing an 8.5 per cent jump since the end of 2022.

The ombudsman said complaints about getting connected to the National Broadband Network or problems with service quality rose 13 per cent.

There was also a 32 per cent jump in complaints about dropouts and intermittent service across both NBN and non-NBN networks.

Overall, there was a drop in complaints that remained unresolved after the ombudsman took action and total complaints were down compared to a year ago.

More than 400 customers had concerns about financial hardship with three quarters reaching out about their mobile phones.

Ombudsman Cynthia Gebert took aim at the “dramatic increase” in problems with internet services and said the proportion of complaints about mobiles was too high.

“I encourage the telcos to keep working on their customer service to ensure that these problems get resolved before people need help from my office,” she said.

An NBN spokeswoman highlighted complaints about faults and connection were down 49 per cent on the same quarter last year.

Improving customer experience was a priority for the network, the spokeswoman said.

“We encourage any customer who is experiencing issues with their service to contact their internet provider in the first instance and we will work with them to resolve any issues,” she said in a statement to AAP.